Design of Plate Surface Displacement Sensors

The present work uses PolyVinyliDene Fluoride (PVDF) film to develop surface displacement sensors for vibrating plates with various boundary conditions. Two constant shape PVDF films are bonded together and to the surface of the plate covering the entire plate. The films are arranged such that the piezoelectric axis 1 of the top film is perpendicular to the piezoelectric axis 2 of the bottom axis. Right angle quadrilaterals patches are etched on the films to create multiple separate sections of the sensors. The output charges of sensor patches covering the same subarea are processed to compute the slopes of the lateral displacement surface of that subarea. The actual plate lateral displacement elevations are calculated from these slopes using forward difference equations. Theoretical analysis and numerical verification show that the proposed sensor can be used to effectively measure the lateral vibration displacements of plates with various boundary conditions. However the accuracy of the measurement is closely related to the number of sensor sections and thus, relatively large number of channels is required for accurate measurements. Furthermore, for non-zero slop conditions at the boundaries, additional point sensors are required.Copyright © 2014 by ASME